Asbestos fiber, after it has been mined and separated from associated non-asbestos minerals and is ready for shipment, is in the form of a fluffy fibrous mass having a density of about 3 to about 20 PCF. Although asbestos can be shipped in this form either in containers or in bulk, in many cases it is desirable to ship the material in a densified form to reduce freight and handling costs.
In the past it has been customary to compact asbestos fiber in pressure-packed bags to a density of about 90 PCF and preferably at least 50 PCF. In this packaging technique the loose mass of asbestos fibers having a density of about 3 to 20 PCF and containing inherent moisture, which normally is less than about 1.5% is given a preliminary compaction to about 25 PCF using a screw conveyor or pug mill to partially de-air and compact the mass. The resultant 25 PCF material is then fed into a bag or a box under pressure to produce a package of asbestos fiber having a density of about 50 PCF. When these packages of asbestos reach the user, normally the asbestos is removed from the container and processed by a device which breaks the consolidated asbestos down into smaller pieces of a size convenient for further opening or dispersion in either wet or dry systems such as a pulper or fiber opener.
This conventional technique of packaging asbestos fiber has provided considerable savings and freight and handling costs as compared with the technique of shipping asbestos loose in low density form in containers such as bags, boxes, etc. The cost of bags or boxes for the 50 PCF technique shipment, however, is still significant. More importantly, a block density of about 50 PCF is still relatively low compared to the theoretical density of asbestos fiber which is about 159 PCF.